Heating and Cooling Unit with Semiconductor Device and Heat Pipe

ABSTRACT

Aspects of the invention support simultaneous operation of a cooling side and a heating side of an apparatus to change the temperatures of a cooling serving surface and a heating serving surface, respectively. A cooling semiconductor device (which may comprise one or more Peltier devices) transfers heat from its top to its bottom while a heating semiconductor device (which may similarly comprise one or more Peltier devices) transfers heat from its bottom to its top. A heat pipe transfers waste heat from the cooling semiconductor device&#39;s bottom to the heating semiconductor device&#39;s bottom and waste cold from the heating semiconductor device&#39;s bottom to the cooling semiconductor device&#39;s bottom.

This application is a continuation of U.S. patent application Ser. No.13/495,643, entitled “Heating and Cooling Unit with Semiconductor Deviceand Heat Pipe” and filed on Jun. 13, 2012, the entire disclosure ofwhich is hereby incorporated by reference, which is acontinuation-in-part of U.S. patent application Ser. No. 13/347,229,entitled “Heating and Cooling Unit with Semiconductor Device and HeatPipe” and filed on Jan. 10, 2012, the entire disclosure of which ishereby incorporated by reference.

TECHNICAL FIELD

Aspects of the disclosure relate to a hot/cold unit for heating and/orcooling an item on a serving surface. In particular, the hot/cold unituses a semiconductor device, such as a Peltier device, and a heat pipe.

BACKGROUND

Perishable foods for home, market, catering and restaurant buffets areconventionally chilled by ice or commercially manufactured containers offreezable material, or by refrigeration systems. When the ice melts andthe freezable material warms, these cooling media lose their ability tokeep foods safe and may render them unsuitable or hazardous forconsumption. Refrigeration systems are bulky and costly, requiringcondensers, coils and harmful chemicals and, further, must be servicedand maintained. Additionally, they are not easily adapted forportability.

Other foods need to be heated or kept warm for home, market, cateringand restaurant buffet service. Conventional sources of heat includeflame and electricity, e.g. by use of alcohol-based combustible gels orby electric hot plates. Flame sources often produce local hot spots anduneven heating and may produce fumes, odors, or other combustionproducts. The indoor pollution and health risks to food service workersand patrons from these combustion products may be viewed with concern bythose in the industry.

In the presentation of food and/or beverages such as for a buffetservice, it is often desirable to store, transport, and/or present thebuffet items in a convenient, presentable fashion. It is often furtherdesirable to provide the items either above or below the ambienttemperature of the presentation environment. Moreover, in-home hostinghas trended upward, and could benefit from equipment improvement.Further, the costs and convenience of improved buffet service, storage,transportation, and/or presentation means may be improved such that theyare more accessible and feasible in the market place.

While traditional servers for heating and/or cooling may not requirefuel or ice to achieve a desired temperature of an item, traditionalservers may rely on a temperature adjusting element in conjunction withan active exchange device, e.g., a liquid circulation pump, tofacilitate energy transfer and thus mitigating the temperature of thetemperature adjusting element. This approach may generate noise maytypically increases the cost of the traditional server.

SUMMARY

An aspect of the invention provides apparatuses, computer-readablemedia, and methods for changing the temperature of a serving surface inorder to cool or heat an item on the serving surface. Heat istransferred to or from the serving surface through a semiconductordevice (e.g., a Peltier device), a heat pipe and a heat sink.

With another aspect of the invention, an apparatus for reducing thetemperature of a serving surface includes at least one Peltier devicethat transfers heat from the serving surface to a heat pipe to a heatexchange device. Alternatively, the apparatus may increase thetemperature of the serving surface by reversing the operation of the atleast one Peltier device.

With another aspect of the invention, a control device activates the atleast one Peltier device from a measured temperature of the servingsurface and a temperature setting. The control device activates the atleast one Peltier device in order change the serving surface accordingto the temperature setting. Moreover, hysteresis may be incorporated sothat control cycling of the at least one Peltier device may be reduced.

With another aspect of the invention, a plurality of Peltier devices maybe partitioned into different subsets so that the control device mayactivate different subsets during different time intervals. When themeasured temperature of the serving surface is outside a temperaturerange, all of the Peltier devices may be activated, while only aselected subset may be activated when the measured temperature is withinthe temperature range and until a hysteresis temperature is reached.

With another aspect of the invention, an apparatus has a cooling sidefor changing the temperature of a cooling serving surface and a heatingside for changing the temperature of a heating serving surface. Acooling semiconductor device transfers heat from its top to its bottomwhile a heating semiconductor device transfers heat from its bottom toits top, where each semiconductor device may comprise one or morePeltier devices. A heat pipe transfers waste heat from the coolingsemiconductor device's bottom to the heating semiconductor device'sbottom and waste cold from the heating semiconductor device's bottom tothe cooling semiconductor device's bottom. The cooling side and theheating side of the apparatus are thermally isolated so that the coolingservice surface and the heating serving surface can operatesimultaneously without adversely affecting the temperature of the otherserving surface.

Various aspects described herein may be embodied as a method, anapparatus, or as one or more computer-readable media storingcomputer-executable instructions. Accordingly, those aspects may takethe form of an entirely hardware embodiment, an entirely softwareembodiment, or an embodiment combining software and hardware aspects.Any and/or all of the method steps described herein may be implementedas computer-readable instructions stored on a computer-readable medium,such as a non-transitory computer-readable medium. In addition, varioussignals representing data or events as described herein may betransferred between a source and a destination in the form of lightand/or electromagnetic waves traveling through signal-conducting mediasuch as metal wires, optical fibers, and/or wireless transmission media(e.g., air and/or space).

Aspects of the disclosure have been described in terms of illustrativeembodiments thereof. Numerous other embodiments, modifications, andvariations within the scope and spirit of the disclosure will occur topersons of ordinary skill in the art from a review of this disclosure.For example, one of ordinary skill in the art will appreciate that thesteps illustrated herein may be performed in other than the recitedorder, and that one or more steps illustrated may be optional inaccordance with aspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features and wherein:

FIG. 1 shows a block diagram of a serving apparatus operating in acooling mode in accordance with an embodiment of the invention.

FIG. 2 shows a block diagram of a serving apparatus operating in aheating mode in accordance with an embodiment of the invention.

FIG. 3 shows a Peltier device in accordance with an embodiment of theinvention.

FIG. 4 shows a heat pipe in accordance with an embodiment of theinvention.

FIG. 5 shows a serving apparatus in accordance with an embodiment of theinvention.

FIG. 6 shows a control device in accordance with an embodiment of theinvention.

FIG. 7 shows circuitry for controlling Peltier devices in accordancewith an embodiment of the invention.

FIG. 8 shows an arrangement of Peltier devices for changing a servingsurface temperature in accordance with an embodiment of the invention.

FIG. 9 shows an arrangement of Peltier devices for changing a servingsurface in accordance with an embodiment of the invention.

FIG. 10 shows a flowchart for controlling a serving apparatus inaccordance with an embodiment.

FIG. 11 shows a flowchart for controlling Peltier devices in accordancewith an embodiment.

FIG. 12 shows a flowchart for controlling Peltier devices in accordancewith an embodiment.

FIG. 13 shows a serving apparatus with a heating side and a cooling sidein accordance with an embodiment.

FIG. 14 shows a serving apparatus with serving surfaces in accordancewith an embodiment.

FIG. 15 shows a portable serving tray in accordance with an embodiment.

FIG. 16 shows a plurality of portable trays stacked in a rack inaccordance with an embodiment.

DETAILED DESCRIPTION

In the following description of the various embodiments, reference ismade to the accompanying drawings which form a part hereof, and in whichis shown by way of illustration various embodiments in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural and functional modificationsmay be made without departing from the scope of the present invention.

FIG. 1 shows a block diagram 100 of a serving apparatus operating in acooling mode in accordance with an embodiment of the invention. Blockdiagram 100 shows the basic elements of the serving apparatus but maynot explicitly show the dimensions and relative placement of theelements. For example, heat pipes 105 and 104 may be bent in ahorizontal plane rather than a vertical plane so that the operation ofthe heat pipes is not adversely affected (e.g., by gravity).

The measured temperature of serving surface 101 is changed bytransferring heat from Peltier devices 102 and 103 through heat pipes104 and 105 and through heat sinks 106 and 107, respectively.

Control device 108 activates and deactivates Peltier devices 102 and 103based on an indication from temperature sensor 109 that is indicative ofthe measured temperature of serving surface 101. Temperature sensor 109is typically placed against serving surface 101 in order to providethermal coupling. For example, when the measured temperature is above acooling temperature setting (i.e., the desired temperature) controldevice 108 provides electrical power to Peltier devices 102 and 103through electrical connections 110 and 111 and connections 112 and 113,respectively.

With some embodiments, heat transfer may be enhanced by fans 114 and 115producing air circulation from heat sinks 106 and 107, respectively, andthrough vent openings 116 and 117, respectively.

FIG. 2 shows a block diagram 200 of a serving apparatus operating in aheating mode in accordance with an embodiment of the invention. Withsome embodiments, the serving apparatus may be the same servingapparatus as with block diagram 100.

Control device 208 reverses the transfer of heat with respect to blockdiagram 100 by reversing the electrical polarity of electricalconnections 210 and 211 and connections 212 and 213. (As will bediscussed, the Peltier effect is a reversible process.) Consequently,heat flows to serving surface 201 to heat it.

FIG. 3 shows Peltier device 300 in accordance with an embodiment of theinvention. However, some embodiments may use other types ofsemiconductor devices that provide similar heating and/or coolingcharacteristics. Heat is transferred between top side 351 and bottomside 352 based on the Peltier effect. Thermoelectric cooling by Peltierdevice 300 uses the Peltier effect to create a heat flux between thejunctions of two different types of materials. Peltier device 300 may beclassified as a heat pump. When direct current is provided to Peltierdevice 300, heat is moved from one side to the other. Peltier device 300may be used either for heating or for cooling since the Peltier effectis reversible. For example, heat may be transferred from top side 351 tobottom side 352 to cool a serving surface by providing electrical powerat terminals 314 and 315. Moreover, the direction of the heat transfermay be reversed (i.e., from bottom side 352 to top side 351) in order toheat the serving surface by reversing the polarity of the electricalpower at terminals 314 and 315.

Peltier device 300 comprises a plurality of N type and P typesemiconductor grains 301-309 that are electrically interconnectedthrough electrical conductor arrangements 310 and 311. Ceramic layers312 and 313 provide thermal conductivity as well as electrical isolationso that Peltier device 300 is able to cool or heat a serving surface.With some embodiments, the serving surface and heat pipe are thermallycoupled to ceramic layers 312 and 313, respectively.

With some embodiments, one or more Peltier devices may be used toexchange heat with the serving surface. For example, with the embodimentshown in FIG. 5, four Peltier devices may provide faster cooling thanwith one Peltier device. Additional Peltier devices may be used;however, electrical power and physical constraints may be factors thatlimit the number of Peltier devices.

FIG. 4 shows heat pipe 400 in accordance with an embodiment of theinvention. With some embodiments, heat pipe 400 is a heat-transferdevice that combines the principles of both thermal conductivity andphase transition to efficiently manage the transfer of heat between twosolid interfaces. At the hot interface within heat pipe 400, which istypically at a very low pressure, a liquid (fluid) is in contact with athermally conductive solid surface that turns into a vapor by absorbingheat from the surface. The vapor condenses back into a liquid at thecold interface, releasing the latent heat. The liquid then returns tothe hot interface through either capillary action or gravity action,where it evaporates once more and repeats the cycle. In addition, theinternal pressure of the heat pipe may be set or adjusted to facilitatethe phase change depending on the demands of the working conditions ofthe thermally managed system. With some embodiments, heat pipe 400 doesnot contain mechanical moving parts and typically requires little or nomaintenance.

Heat pipe 400 may be a heat-transfer device that combines the principlesof both thermal conductivity and phase transition to efficiently managethe transfer of heat between two ends. With traditional systems, aradiator using single-phase convection with a high-speed motor oftenprovides heat transfer. However, heat pipe 400 can transfer the heatefficiently without a high-speed motor.

Heat pipe 400 transports heat from portion 452 to portion 451. Heat pipe400 comprises casing 401, wick 402, and vapor cavity 403. Casing 401 maycomprise a sealed pipe or tube made of a material with high thermalconductivity such as copper or aluminum at both hot and cold ends.Working fluid evaporates to vapor absorbing thermal energy at event 404.Examples of such fluids include water, ethanol, acetone, sodium, ormercury. The vapor migrates along cavity 403 from portion 452 (hightemperature end) to portion 451 (low temperature end). The vaporcondenses back to fluid and is absorbed by wick 402 at event 406, andthe fluid flows back to portion 402 through wick 402.

With some embodiments, referring to FIG. 5, heat pipe 503 comprises asealed pipe or tube made of a material with high thermal conductivity,i.e., copper at both hot and cold ends. For example, a copper pipe ortube may be approximately 300 MM long with a diameter of approximately 8mm. Heat pipe 503 is typically constructed with a tube shell, wick andend caps. Heat pipe 503 may be drawn into negative pressure and may befilled with the fluid such as pure water. Wick 402 is typicallyconstructed with a capillary porous material. Evaporation of the fluidoccurs at one end of heat pipe 503, while condensation occurs at theother end. When the evaporation end is heated, the capillary action inthe fluid evaporates quickly. With a small gravity difference betweentwo ends, the vapor flows to the other end, releasing heat. The vapor isthen re-condensed into fluid, which runs along the porous material bycapillary forces back into the evaporation end. This cycle is repeatedto transfer the heat from the one end to the other end of heat pipe 503.This cycle is typically fast, and the heat conduction is continuous.Good performance of the wick is often characterized by:

-   -   1. Large capillary action or small effective aperture of wick,    -   2. Smaller fluid flow resistance, which have higher        permeability,    -   3. Good thermal conductivity characteristics, and    -   4. Good repeatability and reliability in the manufacturing        process.

Referring to FIG. 4, heat pipe 400 may have bends in order to route theheat transfer to or from a heat exchange device providing that the bendsto not adversely affect the capillary or gravity action of heat pipe400. For example, referring to FIG. 5, heat pipe 503 is bent in ahorizontal plane to route the heat between Peltier device 502 and heatsink 505.

FIG. 5 shows serving apparatus 500 in accordance with an embodiment ofthe invention. While serving apparatus 500 is depicted in the coolingmode, apparatus 500 may be used to heat aluminum plate 501 (whichfunctions as the serving surface on which an item is placed) based onthe previous discussion.

Peltier device 502 is thermally coupled to serving surface 501 andcopper block 504, where the top side (corresponding to ceramic layer 312as shown in FIG. 3) is physically situated against serving surface 501and the bottom side (corresponding to ceramic layer 313) is physicallysituated against copper block 504. Thermal conductivity may be enhancedby ensuring the flatness of the installation surface, and coating thecontact surface with a thin layer of heat conduction silicon grease.Also, in order to avoid fracturing the ceramic layers of Peltier device502, the pressure against the layers should be even and not excessivewhen fixing device 502.

Heat pipe 503 is thermally coupled to Peltier device 502 through copperblock 504 so that heat flows along heat flow 509 a and 509 b. However,with some embodiments, heat pipe 503 may be directly placed againstPeltier device 502. Heat pipe 502 transports heat along heat flow 509 bby traversing through copper block 504 via branches 507 a-507 c and heatsink 505. Heat is thus transported along heat flow 509 c and into thesurrounding environment of serving apparatus 500.

With some embodiments, heat sink 505 may be constructed from copperand/or aluminum in order to achieve performance, size, and costobjectives.

With some embodiments, fan 506 operates when apparatus is operating inthe cooling mode. However, with some embodiments, fan 506 may operate inthe heating and/or cooling modes. Fan 506 assists in the transfer ofheat by drawing in cool air 510 a and 510 b so that heat sink 505 may bekept to a smaller size than without fan 506. With some embodiments, thespeed of fan 506 may be changed based on the temperature of servingsurface 501. For example, the speed may be increased when the differenceof measured temperature of serving surface 501 and the desiredtemperature increases. However, with some embodiments, the speed of fan506 may be fixed when fan 506 is activated and may operate during theentire duration of operation.

With some embodiments, while not explicitly shown in FIG. 5, a coolingfan may circulate air to provide inner air convection within the servingchamber (within serving cover 508 and serving plate 501) to enhance thecooling of food within the chamber. With some embodiments, a fan maysupport inner air convection when the apparatus is operating in theheating mode.

FIG. 6 shows control device 600 for controlling apparatus 100(corresponding to control device 108 as shown in FIG. 1), apparatus 200(corresponding to control device 208 as shown in FIG. 2), and apparatus500 (as shown in FIG. 5) in accordance with an embodiment of theinvention. Processing system 601 may execute computer executableinstructions from a computer-readable medium (e.g., storage device 604)in order provide verify communication redundancy for a network, Memory602 is typically used for temporary storage while storage device 504 maycomprise a flash memory and/or hard drive for storing computerexecutable instructions and a profile image. However, computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage of informationsuch as computer readable instructions, data structures, program modulesor other data. Computer storage media include, but may not be limitedto, random access memory (RAM), read only memory (ROM), electronicallyerasable programmable read only memory (EEPROM), flash memory or othermemory technology, CD-ROM, digital versatile disks (DVD) or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to store the desired information and that can be accessed byprocessing system 601. The executable instructions may carry out any orall of the method steps described herein.

With some embodiments, processing system 601 may correspond to one ormore processors and storage device 604 may correspond to one or morememories.

Control device 600 may be implemented as one or more ASICs or otherintegrated circuits (e.g., a single chip computer) having instructionsfor performing operations as described in connection with one or more ofany of the embodiments described herein. Said instructions may besoftware and/or firmware instructions stored in a machine-readablemedium and/or may be hard-coded as a series of logic gates and/or statemachine circuits in one or more integrated circuits and/or in one ormore integrated circuits in combination with other circuit elements.

With some embodiments, control device 600 supports different controlcapabilities for heating and/or cooling. For example, device 600 mayobtain a temperature setting (desired temperature) from a user throughan input device and control one or more Peltier devices (e.g., Peltierdevices 802-805 as shown in FIG. 8) to compensate for environmentalfactors in order to approximate the desired temperature. Control device600 may also sense when cover 508 (as shown in FIG. 5) is open (e.g.through a switch not explicitly shown), and control the Peltier devicesaccordingly. For example, control device 600 may activate the Peltierdevices for a longer period of time when cover 508 is open than when itis shut.

FIG. 7 shows circuitry 700 for controlling Peltier devices in accordancewith an embodiment of the invention. While some of the functionality ofa serving apparatus may be implemented with a control device (e.g.,control device 600 as shown in FIG. 6), some or all of thefunctionalities may be implemented with separate circuitry, e.g.,circuitry 700. For example, circuitry 700 controls the activation of thePeltier devices by a comparator 701 comparing temperature setting 704and measured temperature 703. Comparator 701 may have hysteresischaracteristics so that once Peltier device 706 is activated byproviding electrical power from source 705 through power switch 702,activation continues until the serving surface reaches a hysteresistemperature.

FIG. 8 shows a collection of Peltier devices for changing a servingsurface temperature in accordance with an embodiment of the invention.Embodiments may support one or more Peltier devices in order to increaseor decrease the temperature of a serving surface. With some embodiments,as shown in FIG. 8, four Peltier devices 802-805 may heat or coolserving surface 801. Some or all of the Peltier devices may be activatedat one time. For example, when the temperature of serving surface 801 iswithin a temperature range, Peltier devices 802-805 may be deactivated.When the measured temperature of serving surface 801 is outside thetemperature range, all of the Peltier devices 802-805 are activated.(This approach is incorporated in flowchart 1100 as shown in FIG. 11 andwill be further discussed.) However, with some embodiments, only aproper subset of Peltier devices (e.g., devices 802 and 805 or devices803 and 804) is activated at a given time when the temperature isoutside the temperature range. Moreover, different subsets may beactivated in a sequenced manner in order to provide more consistentthermal properties, such as more even cooling and/or heating, overserving surface 801. For example, a first subset and a second subset maybe activated and deactivated, respectively, during a first time durationwhile reversing activation states during the second time duration.

Some embodiments may support a greater number of Peltier devices.However, the number of Peltier devices may be limited by physicalconstraints and/or electrical power limitations. FIG. 9 shows acollection of sixteen Peltier devices 902-917 for changing servingsurface 901 in accordance with an embodiment of the invention. Asdiscussed previously, some or all of devices 902-917 may be activated atthe same time. Devices 902-917 may be partitioned into a pluralitysubsets, e.g., a first subset including devices 802, 805, 807, 808, 811,812, 814, and 817, a second subset including 802, 804, 807, 809, 810,812, 815, and 817, and third subset including devices 803, 805, 806,808, 811, 813, 814, and 816, where some or all of the subsets may haveoverlapping members.

With some embodiments, the same Peltier devices may be used fordifferent modes of operation. For example, referring to FIG. 8, Peltierdevices 802-805 may be used both for heating and cooling.

With some embodiments, different Peltier devices may be used fordifferent modes of operation. For example, Peltier devices 802 and 805may be used for cooling while Peltier devices 803 and 804 may be usedfor heating. As another example, Peltier devices 802-805 may be used forcooling while only Peltier devices 502 and 805 are used for heating.

FIG. 10 shows flowchart 1000 for controlling a serving apparatus inaccordance with an embodiment. At block 1001, a control device (e.g.,control device 108 as shown in FIG. 1) reads the measured temperature ofthe serving surface (e.g., surface 101) from the temperature sensor(e.g., sensor 109). At block 1002, the control device determines whetherto activate some or all of the Peltier devices at block 1003. With someembodiments, selected Peltier devices (i.e., all or some of the Peltierdevices) may be activated until the measured temperature reaches ahysteresis temperature so that a hysteresis characteristic isincorporated. For example, the temperature setting may be 35° F. whenthe serving apparatus is operating in the cooling mode. In such a case,the selected Peltier devices may be activated until the serving surfaceis cooled down sufficiently so that the measured temperature reaches 33°F. (the hysteresis temperature). The hysteresis temperature is typicallyoffset from the temperature setting by several degrees so that controlcycling is reduced. Different exemplary procedures for controlling thePeltier devices will be discussed in FIGS. 11 and 12.

At block 1004, the control device determines whether to activate one ormore fans (e.g., fans 114 and 115). For example, with some embodimentsthe fans may be activated at block 1005 only when the measuredtemperature is outside a temperature range to assist transferring heatwith the environment of the serving apparatus. However, with someembodiments, a fan may be activated only for specific operating modes,e.g., a cooling mode or a heating mode.

FIG. 11 shows flowchart 1100 for controlling Peltier devices inaccordance with an embodiment. At block 1101 a control device obtains ameasured temperature of a serving surface from a temperature sensor andthe temperature setting (desired temperature) of the serving surfacefrom a user input. At block 1102, the control device determines the modeof operation, i.e., cooling or heating. Based on the mode of operation,the control device determines whether to activate the Peltier devicesbased on the measured temperature, temperature setting, and hysteresistemperature at blocks 1103-1108.

At block 1103, the control device operates in the cooling mode anddetermines whether the measured temperature exceeds the coolingtemperature setting. If so, the control device activates the Peltierdevices until the measured temperature is less than or equal to thecooling hysteresis temperature at block 1104. Otherwise (i.e., themeasured temperature does not exceed the cooling temperature setting),the control device deactivates the Peltier devices at block 1105.

At block 1106, the control device operates in the heating mode anddetermines whether the measured temperature is less than the heatingtemperature setting. If so, the control device activates the Peltierdevices until the measured temperature is greater than or equal to theheating hysteresis temperature at block 1107. Otherwise (i.e., themeasured temperature does not exceed the cooling temperature setting),the control device deactivates the Peltier devices at block 1108.

FIG. 12 shows flowchart 1200 for controlling Peltier devices inaccordance with an embodiment. Flowchart 1200 is similar to flowchart1100, where blocks 1201 and 1202 correspond to blocks 1101 and 1102,respectively. However, process 1200 activates all of the Peltier deviceswhen the measured temperature is outside a temperature range (e.g.,between the temperature setting and the hysteresis temperature) atblocks 1204 and 1207 and a selected subset of the Peltier devices whenthe measured temperature is within the temperature range at blocks 1205and 1208. When operating at blocks 1205 and 1208, the control device mayselect different subsets from the plurality of Peltier devices andsequence through the different subsets. For example, referring to FIG.9, the control device may first select and activate the first subset fora first time duration, followed by the second subset, followed by thethird subset, followed by the first subset, and so forth.

FIG. 13 shows a serving apparatus 1300 with a heating side 1301 and acooling side 1302 in accordance with an embodiment. Heating side 1301and cooling side 1302 may operate at the same time so that heatingserving surface 1305 may be heating one food item (e.g., hot cereal forbreakfast) while cooling serving surface 1303 may be simultaneouslycooling another food item (e.g., orange juice for breakfast).

Cooling serving surface 1303 is cooled by Peltier device 1304transferring heat from its top to bottom, where Peltier device 1304 isthermally coupled to surface 1303. Heating service surface 1305 isthermally coupled to Peltier device 1306, which transfers heat from itsbottom to its top. Consequently, waste heat is generated at the bottomof Peltier device 1304 while waste cold (loss of heat) is generated atthe bottom of Peltier device 1306.

With some embodiments, Peltier device 1304 and/or Peltier device 1306may comprise a plurality of plurality of Peltier devices similarly shownin FIGS. 8 and 9.

A first portion of heat pipe 1307 is thermally coupled to Peltier device1304 while a second portion of heat pipe 1307 is thermally coupled toPeltier device 1306, in which the operation of heat pipe 1307 is similarto the operation of heat pipe 400 as shown in FIG. 4. Consequently,waste heat is transferred from Peltier device 1304 to Peltier device1306, which absorbs some of the waste heat. On the other hand, wastecold is transferred from Peltier device 1306 to Peltier device 1304,which utilizes the cold in order to lower its operating temperature. Asa result, waste heat and waste cold may be used by Peltier devices 1304and 1306 that would have otherwise been expended into the surroundingenvironment.

Heat pipe 1307 may be directly coupled to Peltier device 1304 and/orPeltier device 1306. However, heat pipe 1307 may be thermally coupled toambient air adjacent to the bottom of Peltier device 1304 and/or Peltierdevice 1306. With some embodiments, heat pipe 1307 may be thermallycoupled to Peltier device 1304 and/or Peltier device 1306 throughanother material (e.g., similar to copper block 504 as shown in FIG. 5).

With some embodiments, heat pipe 1307 may be directly routed betweenPeltier devices 1304 and 1306, where heat pipe 1307 provides acontinuous connection between the hot side and the cold side of Peltierdevices 1304 and 1306, respectively. Consequently, separate heat sinks(heat exchange device) and fans (e.g., as shown in FIGS. 1, 2, and 5)may not be required because the opposite Peltier device may function asthe heat sink for the other Peltier device. For example, the phasechange (liquid to gas and/or gas to liquid) of heat pipe 1307 may causeheat/cold flow from one Peltier device to the other so that separateheat sinks and/or fans may not be needed to cause the temperature changeto influence the heat/cold flow.

With some embodiments, heat pipe 1307 may be routed through a heatexchange device to assist in expending waste heat and/or waste cold.Heat pipe 1307 may have bends (not explicitly shown in FIG. 13) in orderto route the heat transfer to or from a heat exchange device providingthat the bends to not adversely affect the capillary or gravity actionof heat pipe 1307. One or more fans 1308 and 1309 and/or heat exchangedevices (not explicitly shown in FIG. 13) may be positioned in thevicinity of heat pipe 1307 to assist in the exchange of waste heatand/cold.

Thermal barrier 1308 provides thermal separation (isolation) betweenheating side 1301 and cooling side 1302 so that heating serving surface1305 and cooling serving surface 1303 do not adversely affect eachother.

While serving apparatus 1300 may support one heating surface (surface1305) and one cooling surface (surface 1303), a serving apparatus maysupport more than two serving surfaces with some of the embodiments. Forexample, FIG. 14 shows a top view of apparatus 1400 that has heatingsurface 1401 (that may be used for the main course) and two coolingsurfaces 1402 and 1403 (that may be used for a salad and cold desert,respectively). The surface areas and the temperature changes may bedifferent for the different serving surfaces. For example, apparatus1400 may have a plurality of cooling zones, where cooling surface 1402chills a salad while cooling surface 1403 keeps ice cream from melting.Moreover, while serving surfaces 1401-1403 are depicted as rectangularlyshaped, some embodiments may have differently shaped serving surfaces.Also, with some embodiments, surfaces 1401-1403 may have flat or concavesurfaces in order to better contain the served item.

With some embodiments, heat pipes 1404 and 1405 may be routed betweenserving surfaces 1401, 1402, and 1403 to assist in expending waste heatand/or waste cold. Different heat pipe configurations may be supportedsuch as routing a heat pipe between a pair of serving surfaces (e.g.,between serving surfaces 1401 and 1402) or routing a heat pipe acrossmore than two serving surfaces (e.g., 1401, 1402, and 1403).

FIG. 15 shows portable serving tray 1500 that supports serving surfaces1501-1503 that may be used to heat or cool different items in accordancewith an embodiment. Portable serving tray 1500 contains at least onePeltier device (not explicitly shown in FIG. 15) to provide desirabletemperature changes for serving surfaces 1501-1503. In order to haveportable operating characteristics, portable serving tray 1500 may bepowered by portable electrical source 1504 that may be inserted intotray 1500. With some embodiments, portable electrical source 1504 mayinclude a battery and/or fuel cell.

Portable serving tray 1500 may be used in different servingenvironments, including a hospital, hotel, or restaurant. Also,different types of items may be heated or cooled, including food,liquids, and non-eatable items.

FIG. 16 shows serving apparatus 1600 with a plurality of portable trays1500 (as shown in FIG. 15) and 1602-1603 stacked in rack 1601 inaccordance with an embodiment. Portable trays 1500 and 1602-1603 may bestacked into rack 1601 so that trays 1602-1604 can be transported to adesired location. In addition, rack 1600 provides a holding means (e.g.,slots or shelves) so that the portable trays can be inserted into andremoved from rack 1600.

As can be appreciated by one skilled in the art, a computer system withan associated computer-readable medium containing instructions forcontrolling the computer system may be utilized to implement theexemplary embodiments that are disclosed herein. The computer system mayinclude at least one computer such as a microprocessor, digital signalprocessor, and associated peripheral electronic circuitry.

While the invention has been described with respect to specific examplesincluding presently preferred modes of carrying out the invention, thoseskilled in the art will appreciate that there are numerous variationsand permutations of the above described systems and techniques that fallwithin the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:
 1. A method for changing a first measuredtemperature of a cooling serving surface for a cooling zone of anapparatus and a second measured temperature of a heating serving surfacefor a heating zone of the apparatus, the method comprising: transportingwaste heat from a bottom of a cooling semiconductor device to a bottomof a heating semiconductor device; transporting waste cold from thebottom of the heating semiconductor device to the bottom of the coolingsemiconductor device; and activating the heating and coolingsemiconductor devices so that the cooling serving surface and theheating serving surface are operational at a same time.
 2. The method ofclaim 1, wherein the cooling zone and the heating zone are thermallyisolated.
 3. The method of claim 1, wherein the waste heat and the wastecold are transported through a heat pipe.
 4. The method of claim 3,wherein the heat pipe is directly coupled to the cooling semiconductordevice, the heating semiconductor device, or both semiconductor devices.5. The method of claim 1, further comprising: transporting waste heatfrom the cooling semiconductor device and waste cold from the heatingsemiconductor device to a heat exchange device.
 6. The method of claim1, wherein the cooling semiconductor device comprises at least onecooling Peltier device and the heating semiconductor device comprises atleast one heating Peltier device.
 7. The method of claim 3, wherein theheat pipe provides a continuous connection between the coolingsemiconductor device and the heating semiconductor device.
 8. The methodof claim 7, wherein the heating semiconductor device acts as the soleheat sink component for waste heat from the cooling semiconductordevice.
 9. The method of claim 7, wherein no separate heat sinkcomponents, heat exchange devices, or fans assist in the transporting ofthe waste heat.
 10. A serving apparatus comprising: a first portableserving tray comprising: a top surface, the top surface comprising oneor more serving surfaces supported by the first serving tray; and atleast one Peltier device contained within the first serving tray andconfigured to change a temperature of at least one of the one or moreserving surfaces; and a first portable electrical source configured toprovide electrical power to the at least one Peltier device of the firstserving tray; wherein the first portable serving tray is operable whenpositioned at different locations.
 11. The serving apparatus of claim10, further comprising: a rack configured to separately hold a pluralityof portable serving trays, wherein the plurality of portable servingtrays are stackable within the rack and removable from the rack; asecond portable serving tray comprising: a top surface, the top surfacecomprising one or more serving surfaces supported by the second servingtray; and at least one Peltier device contained within the secondserving tray and configured to change a temperature of at least one ofthe one or more serving surfaces; and a second portable electricalsource configured to provide electrical power to the at least onePeltier device of the second serving tray; wherein the second portableserving tray is operable when positioned at different locations.
 12. Theserving apparatus of claim 11, further comprising a thermal barrierisolating the first portable serving tray and the second portableserving tray.
 13. The serving apparatus of claim 10, wherein theportable electrical source comprises one or more of a battery and a fuelcell.
 14. The serving apparatus of claim 10, wherein the portableelectrical source is configured to be inserted into the tray.
 15. Anapparatus comprising: one or more cooling zones, each cooling zonecomprising one or more cooling semiconductor devices configured totransfer heat from a top to a bottom of the cooling semiconductordevice, and one or more cooling serving surfaces thermally coupled withthe top of at least one cooling semiconductor device; one or moreheating zones, each heating zone comprising at one or more heatingsemiconductor devices configured to transfer heat from a bottom to a topof the heating semiconductor device, and one or more heating servingsurfaces thermally coupled with the top of at least one heatingsemiconductor device; and at least one heat transfer device comprising afirst portion and a second portion, the first portion thermally coupledwith the bottom of at least one cooling semiconductor device, the secondportion thermally coupled with the bottom of at least one heatingsemiconductor device, the heat transfer device being configured totransfer waste heat from the bottom of at least one coolingsemiconductor device and transfer waste cold from the bottom of at leastone heating semiconductor device.
 16. The apparatus of claim 15, whereinthe apparatus comprises two or more cooling zones, two or more heatingzones, or a combination thereof.
 17. The apparatus of claim 16, whereinthe heat transfer device comprises at least a third portion, and whereinthe three portions of the heat transfer device are thermally coupled toone or more semiconductor devices of three separate zones of theapparatus.
 18. The apparatus of claim 16, further comprising at least asecond heat transfer device comprising a first portion and a secondportion, the first portion thermally coupled with the bottom of at leastone cooling semiconductor device, the second portion thermally coupledwith the bottom of at least one heating semiconductor device, the secondheat transfer device being configured to transfer waste heat from thebottom of at least one cooling semiconductor device and transfer wastecold from the bottom of at least one heating semiconductor device. 19.The apparatus of claim 15, wherein the heat transfer device is a heatpipe, and wherein no separate heat sink components, heat exchangedevices, or fans assist in the transfer of the waste heat.
 20. Theapparatus of claim 15, wherein the heat transfer device is a heat pipe,and the apparatus further comprises at least one heat exchange device,at least one fan configured to assist in the exchange of waste heat, ora combination thereof.